Internal combustion engine apparatus



March 14, 1961 P, C, HQLDEN ETAL 2,974,489

INTERNAL COMBUSTION ENGINE APPARATUS Filed July 5, 1957 flow rate.

United StatesPatent INTERNAL COMBUSTION ENGINE APPARATUS Paul C. Holden,Mission, Kans., and William A. English, Lees Summit, M0., assignors, bymesne assignments, to the United States of America as represented by theSecretary of the Air Force v Filed July 3, 1957, Ser. No. 670,844 1Claim. (Cl. Gli-39.74)

This invention relates to a centrifugal liquid injection structure foran internal combustion power plant, more particularly to a centrifugalliquid injection structure for delivering liquid in nely Iatomized form,and has for an object to provide an improved structure of this type.

Heretofore, numerous rotary arrangements have been proposed employingcentrifugal force for injecting liquid fuel or the like into acombustion chamber. These prior arrangements employed fixed areainjection orices radially spaced from the center of the rotor. Hence thedegree of atomization attained, assuming an adequate constant head ofliquid is maintained, was preponderantly a function lof rotary speed.However, in practice, the liquid liow rate to the rotor and the rotaryspeed are widely variable to suit varying operating conditions. Hencethe liquid head varies with rotary speed and liquid flow rate. Since, ata selected speed, the liquid head is reduced as the flow rate isreduced, the quality of atomization deteriorates accordingly. `On theother hand, if at a selected speed the liquid iiow rate is increased toa value higher than it can *be discharged through the orifice, theliquid will overflow. To sumrnarize, it can now be seen that withinjectors having orifices of fixed area best atomization at any selectedsneed of the rotor occurs at only one value of liquid In view of theabove,'it is a further object of the invention'to provide a centrifugalliquid injection structure which effects a fine degree lof atomizationover a wide range of rotattional speeds and/or liquid flow deliveryrates. Y

Another object is to provide a centrifugal liquid injection rotor inwhich the effective area of the injection orifice is varied 4as a directfunction of the liquid liow rate, so that increased ow rate can beaccommodated by the rotor, thereby eliminating the possibility ofoverflow due to -overfilling of the rotor.

A Briefly, in accordance with the invention there is provided arotorhaving a plurality of radially extending tubular arms communicating attheir inner ends with a a centrally disposed drurnand jointlyrotatabletherewith. ,Each of the arms is provided with substantiallyidentical liquid injection structure including an injection oricelprovided adjacent its outermost tip and controlled by a piston slidablyreceived within the arm adjacent the orifice.. Hence, a description -ofthe operation of one liquid vinjection structure will suiiice toVexplain the invention.

Liquid fuel is delivered by a stationary conduit to the interior of the4drum and, Yas the rotor is rotated, the f uel will be urged intotbetubular arm by the centrifugal forces set up, to establish a liquidcolumn. The piston is also urged radially outwardly by the .centrifugalforces in the-direction -to block the injection orifice. However, theforces urging the piston radially outwardly are opposed byfthe forces`acting on the liquid column in the arm so that the piston attains abalanced position in ice 2 which the injection orifice is partiallyopened. With constant fuel liow rate, should the speed of the rotor beincreased or decreased, the centrifugal forces acting on the liquidcolumn and the piston are proportionately increased or decreased,respectively, to momentarily maintain the piston in substantially thesame balanced position. However, the change in fuel pressure `across theso far unchanged orifice area, causes a momentary increase or decreasein the rate at which fuel is injected from the orifice thus decreasingor increasing the fuel level in the arm. This causes the piston to seeka new equilibrium position. By proper design, a suitable large `liquidhead pressure can be maintained in the column, regardless of variationsin motor speed. For example, by properly proportioning the piston memberso that its centrifugal force is somewhat less than that of the liquidcolumn when the arm is completely filled, the piston member will bemovable to completely unblock the orifice to increase the injection ratesuiciently to maintain the height of the column of liquid to a valueless than the length of the arm, thereby preventing liquid overliow fromthe drum. Accordingly, a high degree of fuel atomization is maintainedthrough a wide range ofv rotor speeds. However, as the rate at whichfuel delivered to the drum is varied, the height of the column of liquidin the arm is varied, thus moving the piston in the direction toincrease the area of 4the injection orifice with increase in flow rateand in the direction to decrease the area of the injection orifice withdecrease in ow rate. With this arrangement a consistently high degree offuel atomization is attained, even though the fuel flow rate and/or therotary speed of the rotor is varied. l

Although not specifically limited thereto, the improved centrifugalliquid injector is primarily applicable for injecting fuel into thecombustion chamber of a gas turbine power plant and, when so employed,may be attached to the turbine-compressor rotor aggregate forv jointrotation therewith.

The above and other objects are effected by the invention as will beapparent fromthe following description and claims, taken in connectionwith the accompanying drawing, forming a part of this application, inwhich:

Fig. 1 is an axial schematic sectional view, with the lower radialportion omitted, of -a typical axial-How aviation turbojet engine havingthe invention incorporated therein;

Fig. 2 is a cross-sectional view taken on line Il-II of Fig. l, lookingin the direction of the arrows; Y

Fig. 3 is an enlarged fragmentary sectional view taken on line Ill-III,looking in the direction of the arrows; and

Fig. 4 is a transverse sectional view taken on line IV-IV of Fig. 3. u

Referring to the drawing in detail, especially Fig. l, there is shown aninternal combustion power plant which for purposes of illustration hasbeen shown as an aviation turbojet engine 10 of the well-known axial owtype.

As is well known in the art, the engine is provided with an outertubular shell 11 having an axial-flow air compressor section 12, a fuelcombustion section 13 and a gas turbine section 14 disposed in axialalignment with each other Within the shell 11. provided with a bladedrotor 15 and a bladed stator 16 complementary therewith. The turbine 14,in similar manner, is provided with a bladed rotor 17 and a bladedstator 18 complementary therewith. Also, suitable liner structure 19 isprovided, which, jointly with the outer q shell 11, `defines an annularpassageway 20 for air liow.

through the engine.V The rotors 17 and 15 are connected The compressorsection 12 is,

to each other for joint operation by shaft 21 and form a rotor aggregatewhich is suitably supported for rotation by means (not shown).

As thus far described, the engine operates in. a .wellknown manner toreceive air througha forwardly directed air intake 22, which air is thenpressurized in the compressor section 12 and thence delivered by thepassageway 20 into the combustion section 13 wherein it is combined withfuel admitted thereto, in a manner subsequently to be described, to formhot motive gases which are then directed through the turbine rotor 17 torotate the same and eventually are expelled through a rearwardlydirected exhaust nozzle 23 to the ambient atmosphere in the form of apropulsive jet.

In accordance with the invention, there is provided a fuel injectingsystem 24 for admitting liquid fuel in highly atomized form to thecombustion section 13. The fuel injecting system 24 comprises a rotor 25mounted on the shaft 21 and having a drum 26 of circular shape. hc drum26 defines an annular fuel receiving chamber Z7 having a forwardlydirected opening 23 concentric with the shaft 21. A plurality of tubulararms 29 are attached to the periphery of the drum 26 and extend radialiyoutwardly therefrom, as best shown in Figs. l and 2. Since the arms 29may be identical to each other, only one of the arms will be described.The arm 29 is formed of generally circular cross-section, as shown inFig. 4, and is provided with an elongated passageway 30 communicating atits inner end 31 with the drum 26 and extending outwardly therefrom thefull length of the arm. The arm 29 is provided with a fuel injectiohaperture 32 adjacent its outer tip and within the arm 29 there isprovided a tubular wall member 33 having an elongated bore 34 formedtherein. Within the bore 34 there is slidably disposed a piston valvemember 35 which divides the bore 34 into an outer chamber 36a and aninner chamber 36h. The outer chamber 36a communicates with thepassageway 30, by means of a radially outwardly facing opening 37 formedin the wall member 33, and with the injection aperture 32. The chamber36h is vented to the atmosphere by means of a small vent opening 38.

Fuel is directed into the fuel collecting chamber 27 by means of a fuelconduit 39 which is stationarily received in a hollow strut member 4t)extending across the air passageway 20. As illustrated, the strut member40 is connected at one end to the outer shell 11 of the engine andextends through the core member 19, as best shown in Fig. l. The conduit39 has a curved outlet end portion 41 which extends into fuel collectingchamber 27 through the opening 28 and is preferably directed (as shownin Fig. 2) in the direction of rotation of the rotor.

The combustion section 1'3 includes stationary outer and innerforaminated wall structures 43 and 44, respectively, of annular shapeconcentrically mounted relative to the axis of rotation of the shaft 21and defining a fuel combustion chamber 45. The wall structures 43 and 44are provided with radially disposed and spaced end walls 46 and 47,respectively, which jointly define an annular opening 4S for admittingfuel into the combustion chamber 45 for combustion purposes.

In operation, after the rotor aggregate (including rotors 15 and 17 andthe shaft 21) is cranked by any suitable means (not shown) to start theengine, fuel is delivered to the conduit 39 by suitable fuel fiowregulating mechanisrn (not shown) in desired volume to sustain`operation of the engine. The fuel is directed into the fuel collectingchamber 27 of the drum 26 through the conduit outlet 41 and then, due tothe rotary action of the rotor 25, the fuel is thrown in radiallyoutward direction by centrifugal force into the arm 29. Concomitantlytherewith, the piston valve member 35 is moved in radially outwarddirection by centrifugal force to momentarily block the orifice 32. Thefuel column accumulating in the passageway 30. provides a head pressureeffective through the opening` 37 to urge the piston valve member inradially inward direction, thereby to unblock the orifice. Since theforces acting on the piston valve 35 are in direct opposition to eachother, the piston valve will assume a stable position somewhere betweenthe maximum open position and the closed position, depending upon thcheight of the liquid column in the arm, to permit fuel to ow from thepassageway 30 through the opening 37 into the chamber 36a and thence tobe ejected by the orifice 32 in finely atomized form. Since the aperture32 is in rotary alignment with the annular opening 48 in the combustionsection 13, the atomized fuel issuing through the orifice 32 will bedirected into the combustion chamber 45 in suitable form for combustion.

During normal operation it may be desirable to increase the rotationalspeed of the rotor aggregate (17 and l5). During such increasedrotational speed conditions, the centrifugal force acting on the pistonvalve 35 will increase, thereby increasing the radially outwardly urgingeffect thereon. However, since the rotational effect also increases thecentrifugal force on the fuel column within the chamber 3ft in a similarmanner, the net result upon the piston valve 35 is the same as before,so that its position remains unchanged as long as the height of liquidcolumn remains unchanged. However, this change in rotational speedcauses a momentary change in fuel pressure across the so `far unchangedorifice area and tends to change the fuel level. The piston value 35will then moveto a new equilibrium position.

However, when it is desired to increase the thrust of the engine byincreasing the rate at which the fuel is injected thereinto, the rate offuel flow through the fuel conduit 39 is increased. Hence, a greatervolume of fuel is momentarily collected within the arm 29 and the heightof the fuel column is momentarily increased, thereby increasing thefluid force on the piston valve 35 in opening direction. During suchconditions, the piston valve 35 moves radially inwardly to a new stableposition in which the effective area of the orifice 32 is increased. Atthe new equilibrium position, the head of fuel above the outer piston`face will actually be decreased slightly. since less fuel force isrequired to balance the lower centrifugal force of the piston inertia inits inwardly moved position. The height of fuel in the arm 29, however,increases slightly. It will be seen that the fuel pressure decreaseswith increasing fiow.

Conversely, when it is desired to reduce the thrust of the engine, theamount of fuel delivered through the conduit 39 is reduced. During suchconditions, the height of the liquid within the arm 29 is momentarilyreduced, thereby reducing the force upon the piston valve 35 in openingdirection and allowing the valve to move radially outwardly to a newstable position in which the effective area of the orifice 32 isreduced. Hence, even though the fuel flow rate to the engine is reduced,the pressure is actually increased slightly to maintain the high degreeof atomization of fuel injected into the combustion chamber 49.

The vent opening 38 is effective to permit freedom of movement of thepiston valve 35 within the bore 34 so that the piston valve is solelyresponsive to the force of the fuel column in the arm 29.

The piston valve 35 in the embodiment described is of greater specificgravity than the liquid fuel and, as illustrated, is of solid form.However, the exact density of the piston valve may be modified to suitthe application regardless of the specific gravity of the material ofwhich it is formed. For example, although not specifically shown, if thespecific gravity of the material forming the piston valve is excessivefor a particular application, the piston valve may be formed with ahollow interior or may be shortened in lengthwise direction for accurateperformance.

If the density of the piston valve is less than that of the fuel, thepiston valve will essentially oat in the liquid and the vent 38 to theatmosphere becomes unnecessary.

The collecting chamber 27 distributes the incoming fuel substantially ata luniform rate to each of the arms 29. Hence, adequate fueldistri-bution is assured in operation, obviating highly undesirable hotspots in the the combustion chamber 45. Also, since the head pres'- sureattained by the columns of fuel in the arms 29 is of a relatively highorder, atomization of the fuel as it issues through the injection orices32 is assured.

It will now be seen that the invention provides a fuel injection systemfor an internal combustion engine which delivers the fuel into thecombustion section of the engine in finely atomized form over a widerange of rotational speeds and/or of fuel fio-ws.

It will further be seen that since the orifice 32 is variable by thesliding piston valve 35, the effective open area of the orifice 32 isnot affected by variables other than the height of the liquid fuel inthe anm 29. Also, since the piston valve is slidably mounted within thebore 34, and since the bore 34 has its outer chamber 36a lled withliquid fuel during all conditions of operation, the piston valve 35 willoperate smoothly and with a minimum of friction.

Partial clogging of the injection orifice 32 by foreign particles isquickly cleared, since during such conditions the momentary decrease ineffective area of the orifice causes the height of the liquid column tomomentarily increase with :attendant movement of the piston valve inorifice yarea increasing direction.

While the invention has been shown in but one form, it will be obviousto those skilled in the art that it is not so limited, but issusceptible of various changes yand modiiications without departing fromthe spirit thereof.

What is claimed is:

In an internal combustion engine, wall structure deiining 4an annularfuel combustion chamber and having spaced portions defining an annularopening for permitting injection of liquid into said combustion chamber,a liquid injection 4rotor structure for injecting liquid solely bycentrifugal Afonce in `atomized form into said combustion chamberthrough said annular opening, a conduit for delivering liquid to saidrotor structure, said rotor structure being rotatable relative to saidconduit vand said fuel combustion chamber, said rotor structure having adrum defining an open-ended liquid collecting chamber concentricallydisposed relative to the rotational axis of said rotor structure, saidconduit having an outlet opening disposed in said collecting chamber, atubular arm having an elongated passageway communicating with saidliquid collecting chamber and extending outwardly therefrom in radialdirection, said tubular arm having a liquid injection oricecommunicating at a right angle with the radially outer portion of saidpassageway and disposed in rotary align-ment with said annular openingin the combustion chamber, a freely movable piston valve membercooperatively associated with said orifice `for modifying the eiectivearea of said orifice, a tubular wall member carried by said arm anddefining a radially extending bore for slidably supporting said pistonmember, said piston member dividing said bore into first and secondchambers, said rst chamber communicating with said passageway and saidsecond chamber communicating with the atmosphere externally of saidrotor structure, and said piston member being subject solely to theopposing forces of centrifugal force induced therein in one directionand the centrifugal force induced in the column of liquid in saidpassageway in the opposite direction to modify the 'area of saidorifice, said piston having a mass of lower value than a mass of liquidequal to the volume of said passageway, and being effective to maintainthe height of the column of liquid to a value less than the length ofsaid passageway.

References Cited in the le of this patent UNITED STATES PATENTS2,416,389 Heppner et al Feb. 25, 1947 2,568,921 Kroon Sept. 25, 19512,596,161 Murdock et al. May 13, 1952 2,622,394 Murdock et al. Dec. 23,1952 2,627,718 Edelfelt et al Feb. 10, 1953 2,720,750 Schelp Oct. 18,1955 2,861,425 Williams Nov. 25, 1958

